Diagnosing sulphur poisoning of emission control catalysts with quantitative hard X-ray nanotomography

Natural gas as energy source is expected to proliferate during a transitional period from fossil fuel to renewable/sustainable energy sources. Pd-based catalysts are typically used in natural gas engines to ensure complete oxidation of CH4. CH4 is the main component of natural gas and a powerful greenhouse gas if released to the environment. However, Pd catalysts are susceptible to sulphur poisoning, which is present as an odorant additive (safety feature) in natural gas power systems. Studies on model catalyst systems have identified symptoms of sulphur poisoning and proposed regeneration pathways, however this has rarely been explored in terms of large technical catalysts. Here we aim to apply hard X-ray holotomography at hierarchical length scales to examine technical Pd-based catalyst honeycombs. Using fresh, poisoned, and regenerated catalysts, we will quantify the catalyst pore structure in 3D space and identify sulphur deposits which block or hinder accessibility to the pores.